Organic acid-modified polymers for golf ball constructions and methods relating thereto

ABSTRACT

The invention is directed to a method of making a neutralized polymer composition (“NPC”) suitable for a golf ball component comprising the steps of: providing an acid copolymer composition; soaking the acid copolymer composition in an organic acid to form a soaked polymeric composition wherein substantially all of the organic acid is absorbed within the acid copolymer composition; providing a cation source in an amount sufficient to neutralize the acid copolymer and organic acid; and melt processing the soaked polymeric composition and cation source to form a neutralized polymer composition. The invention also relates to a method of making a golf ball incorporating the NPC made according to the inventive method and to the resulting golf ball.

FIELD OF THE INVENTION

This invention relates generally to methods for manufacturingneutralized polymers suitable for golf ball constructions as well as tomethods for making golf balls incorporating neutralized polymers and togolf balls incorporating such neutralized polymers.

BACKGROUND OF THE INVENTION

Golf balls, whether of solid or wound construction, generally include acore and at least a cover and/or outer coating. The core may be solid orliquid-filled, and may comprise one piece or have a center with one ormore outer core layers formed about the center. Covers may also beformed of one or more layers. Multi-layer cores and covers are sometimesknown as “dual core” and “dual cover” golf balls, respectively.

The playing characteristics of golf balls, such as spin, feel, CoR andcompression can be tailored by varying the properties of the golf ballmaterials and/or adding additional golf ball layers such as at least oneintermediate layer disposed between the cover and the core. Intermediatelayers can be of solid construction or may be formed of a tensionedelastomeric winding, which are referred to as wound balls. Thedifference in play characteristics resulting from these different typesof constructions can be quite significant.

Cores are generally made using techniques such as compression orinjection molding. Typically, the center is formed by compressionmolding a slug of uncured core material into a spherical structure. Theouter core layers may be formed, for example, by molding compositionsover the center by compression or injection molding techniques. In turn,the intermediate and/or cover layers are applied.

A cover layer(s) may be formed over the outermost of the core orintermediate layer (collectively referred to herein as “ballsubassembly”) using suitable techniques including, for example,compression-molding, flip-molding, injection-molding, retractable pininjection-molding, reaction injection-molding (RIM), liquidinjection-molding, casting, spraying, powder-coating, vacuum-forming,flow-coating, dipping, spin-coating, and the like. In a compressionmolding process, hemispherical shells are generally placed about thesubassembly in a compression mold and fused together under sufficientheat and pressure. In contrast, with an injection molding process, covermaterial is injected about and directly onto the subassembly usingretractable pins, for example.

When a cover layer is formed by a casting process, liquid cover materialis poured into lower and upper mold cavities, into which a subassemblyis lowered at a controlled speed. The subassembly is held in place viapartial vacuum to the point of sufficient gelling, and then the uppermold cavity is mated with the lower mold cavity under sufficientpressure and heat followed by cooling the unit until it can be handledwithout deformation.

Golf ball core and cover layers are typically constructed with polymercompositions such as polybutadiene rubber, polyurethanes, polyamides,ionomers, and blends thereof. Ionomers, particularly ethylene-basedionomers, are a desirable group of polymers for golf ball layers becauseof their toughness, durability, and wide range of hardness values.Further, golf balls incorporating fatty acid neutralized acid polymersare generally known for achieving desirable golf ball propertiesrelating for example to spin, feel, and CoR.

In this regard, fatty acid neutralized acid polymers may be manufacturedby feeding acid copolymers and organic acids into a melt extruder suchas a single or twin screw extruder via separate feed lines, and adding asuitable amount of cation source for neutralizing a desired level ofacid groups present. The ingredients may be intensively mixed prior tobeing extruded as a strand from the die-head.

Several drawbacks have presented from feeding each ingredient into theextruder individually. First, formulation errors occur becausecoordinating the varied feed rates of multiple feed lines can bedifficult. Additionally, the organic acid sometimes fails to distributeuniformly throughout the mixture within the extruder in relation to theacid copolymer, thereby producing a resulting material lackinghomogeneity in localized areas—a quality control issue which increasesthe overall cost of golf ball manufacture.

Accordingly, there remains a need for improved methods for manufacturingneutralized polymers suitable for golf ball constructions as well as tomethods for making golf balls incorporating neutralized polymers and togolf balls incorporating such neutralized polymers which reduce themargin for formulation error and lower manufacturing costs. The presentinvention addresses and solves this need.

SUMMARY OF THE INVENTION

The present invention is directed to a method of making a neutralizedpolymer composition (“NPC”) suitable for use in a golf ball component(core, whether a single solid core or a multi-layer core having a centerand at least one outer core layer, cover, or any intermediate layer)comprising the steps of: providing an acid copolymer compositioncomprising one or more ethylene-acid copolymers; soaking the acidcopolymer composition in one or more organic acids wherein substantiallyall of the organic acid is absorbed within the acid copolymercomposition to form a soaked polymeric composition (“SPC”); optionallyproviding one or more cation sources in an amount sufficient toneutralize at least a portion of the acid copolymer(s) and organicacid(s) to a target level; and melt processing the soaked polymericcomposition and cation source(s) to form an NPC.

Herein, an NPC may be any of the following: a “highly neutralizedpolymer composition”—that is, greater than 80% of acid groups presentare neutralized; a “very neutralized polymer composition”—70%-80% ofacid groups present are neutralized; or a “partially neutralized polymercomposition”—wherein less than 70% of acid groups present areneutralized. And the “target level” of percent acid groups present inthe soaked polymeric composition being neutralized with the cationsource will fall within one of these neutralization ranges.

For example, in one embodiment, the NPC is a highly neutralized polymercomposition wherein the target level of acid groups present beingneutralized with the cation source is greater than about 100%. Inanother embodiment, the NPC is a highly neutralized polymer compositionwherein the target level of acid groups present being neutralized withthe cation source is greater than about 95%. In yet another embodiment,the NPC is a highly neutralized polymer composition wherein the targetlevel of acid groups present being neutralized with the cation source isgreater than about 90%. In still another embodiment, the NPC is a highlyneutralized polymer composition wherein the target level of acid groupspresent being neutralized with the cation source is greater than 80% toabout 90%. In an alternative embodiment, the NPC is a highly neutralizedpolymer composition wherein the target level of acid groups presentbeing neutralized with the cation source is from 85% to 95%. In adifferent embodiment, the NPC is a highly neutralized polymercomposition wherein the target level of acid groups present beingneutralized with the cation source is 81%, or 84%, or 87% or 91%, or93%, or 97%, or about 83%, or about 86%, or about 92%, or about 94%, orabout 96%, or about 98% or 99% or about 100%, or about 105%, or about125%, or about 150%, or about 173%, or about 200%.

Additionally, in one embodiment, the NPC is a very neutralized polymercomposition wherein the target level of acid groups present beingneutralized with the cation source is greater than 70% but less than80%. In another embodiment, the NPC is a very neutralized polymercomposition wherein the target level of acid groups present beingneutralized with the cation source is greater than about 75% and up to80%. In yet another embodiment, the NPC is a very neutralized polymercomposition wherein the target level of acid groups present beingneutralized with the cation source is greater than 70% and up to 78%. Instill another embodiment, the NPC is a very neutralized polymercomposition wherein the target level of acid groups present beingneutralized with the cation source is greater than 73% and less than78%. In an alternative embodiment, the NPC is a very neutralized polymercomposition wherein the target level of acid groups present beingneutralized with the cation source is from about 75% to about 77%. In adifferent embodiment, the NPC is a very neutralized polymer compositionwherein the target level of acid groups present being neutralized withthe cation source is 70%, or 71%, or 74%, or 77% or 79%, or 80%, orabout 73%, or about 76%, or about 79%.

Meanwhile, in one embodiment, the NPC is a partially neutralized polymercomposition wherein the target level of acid groups present beingneutralized with the cation source is less than 70%. In anotherembodiment, the NPC is a partially neutralized polymer compositionwherein the target level of acid groups present being neutralized withthe cation source is greater than about 45% and up to 70%. In yetanother embodiment, the NPC is a partially neutralized polymercomposition wherein the target level of acid groups present beingneutralized with the cation source is 55% and up to 70%. In stillanother embodiment, the NPC is a partially neutralized polymercomposition wherein the target level of acid groups present beingneutralized with the cation source is greater than 63% and less than70%. In an alternative embodiment, the NPC is a partially neutralizedpolymer composition wherein the target level of acid groups presentbeing neutralized with the cation source is from about 35% to about 57%.In a different embodiment, the NPC is a partially neutralized polymercomposition wherein the target level of acid groups present beingneutralized with the cation source is 10%, or 21%, or 34%, or 47%, or59%, or 65%, or about 13%, or about 16%, or about 29%, or about 36%, orabout 42%, or about 53%, or about 57%, or about 64%, or 69%.

Herein, the terms “melt processing” or “melt processed” shall refer tomelt blending two or more ingredients of the inventive composition inpolymer processing equipment at an elevated temperature with asufficient amount of shear mixing for a period long enough to the attainthe desired properties of the end product. Melt processing may beaccomplished by numerous conventional melt blending procedures. In thisregard, the soaked polymeric composition along with a required amount ofcation source(s) necessary to achieve the desired level ofneutralization can be melt processed in a twin-rotor type internalmixer, two-roll mills, or extruded in a single or twin-screw extruder.The melt-processed material is usually formed into slabs, preforms, orpellets at or just after melt processing, which can used immediately orstored easily for molding or blending at a later time.

The above-identified steps of providing an acid copolymer compositionand soaking the acid copolymer composition in an organic acid to form asoaked polymeric composition may advantageously be performed well inadvance of or just prior to the steps of providing the cation source andmelt processing the soaked polymeric composition and cation source. Forexample, in one embodiment, the soaked polymeric composition may bepre-formed, packaged and transported to the manufacturing plant wherethe soaked polymeric composition is then added into the extruder and theremaining aforementioned steps of the method of making the NPC areperformed.

The acid copolymer composition may comprise a powder, particulates,pellets or any other solid form capable of or suitable for absorbing,incorporating and/or otherwise containing the organic acid as a resultof the soaking step. An acid copolymer composition may also include atleast one non-acid polymer. The acid copolymer may be a single acidcopolymer or a mixture of two or more acid copolymers.

Additionally, the organic acid may comprise a single organic acid or ablend of at least two different organic acids. However, the organicacid(s) and acid copolymer(s) should be chosen such that the former is aliquid and the latter is a solid and is not blocked at the temperatureat which the soaking step is performed. Herein, the term “blocked”refers, for example, to significant adhesion between two polymersurfaces. For example, acid copolymer composition pellets are generallyblocked where the pellets adhere to each other inseparably.

In one embodiment, the soaking step may be performed at a temperature ofabout 20° C. or greater. In another embodiment, the soaking step may beperformed at a temperature of from about 25° C. to about 125° C. In yetanother embodiment, the soaking step is performed at a temperature offrom about 40° C. to about 100° C. or greater. In still anotherembodiment, the soaking step is performed at a temperature of from about40° C. to about 60° C. In an alternative embodiment, the soaking step isperformed at a temperature of about 60° C. or greater. In a differentembodiment, the soaking step is performed at a temperature of about 70°C. or greater. The soaking step may also be performed at a temperatureof about 70° C. or greater or from about 80° C. to about 120° C. or fromabout 80° C. to about 110° C. In some embodiments, the soaking step mayrequire a multiplicity or series of temperatures and durations.

For example, in one embodiment, the organic acid is lauric acid, whichhas a melting temperature of 44° C., and the acid copolymer is anethylene-acid copolymer. The lauric acid is provided and maintained at asoaking temperature that is equal to or greater than 44° C. but lessthan a temperature at which the ethylene-acid copolymer blocks.Subsequently, the ethylene acid copolymer is added into the liquidlauric acid and the soaking step is performed until substantially all ofthe organic acid is absorbed within the ethylene-acid copolymer. Wherethe chosen organic acid/organic acid blend is a liquid and theacid-copolymer composition a solid at room temperature, then the soakingstep may optionally be performed at room temperature. Further, if afirst chosen organic acid is not a liquid at room temperature, thesoaking step may nevertheless be performed at room temperature bydissolving the first organic acid in a suitable second organic acid thatis indeed a liquid below room temperature. Once again, the soakingtemperature may be any temperature at which the organic acid or mixtureof organic acids is a liquid and the acid copolymer composition is notblocked. However, generally, soaking at comparatively highertemperatures within the permissible range will allow for incorporationof higher levels of organic acids, shorter soak duration, or both.

In one embodiment, the soaked polymer composition (or SPC) comprises aplurality of acid copolymer solids that have substantially absorbed apredetermined amount of liquid organic acid. In this embodiment of thesoaking step, a predetermined weight % of acid copolymer compositionsubstantially absorbs a predetermined weight % of the organic acid andthe resulting soaked polymeric composition comprises a discrete weightratio of organic acid to acid copolymer composition.

Non-limiting examples of the weight ratio of organic acid to acidcopolymer composition are as follows. In one embodiment, the weightratio is from about 1:9 to about 1:1. In another embodiment, the weightratio is from about 1:3 to about 3:5. In yet another embodiment, theweight ratio is from about 1:5 to about 3.25:5.

More particularly, the weight ratio of organic acid to acid copolymercomposition may have a lower limit of about 1:9 or about 1:5 or about1:4 or about 1:3 or about 1:2 and an upper limit of about 1:2 or about2:3 or about 1:1 or about 3:2 or about 2:1.

Additionally, in one embodiment, the weight ratio of organic acid toacid copolymer composition is about 2:3. In another embodiment, theweight ratio of organic acid to acid copolymer composition is about 1:5.In yet another embodiment, the weight ratio of organic acid to acidcopolymer composition is about 1:1. In still another embodiment, theweight ratio of organic acid to acid copolymer composition is about 1:9.In a different embodiment, the weight ratio of organic acid to acidcopolymer composition is about 2:9. In another embodiment, the ratio oforganic acid to acid copolymer composition is about 3:2.

One advantage of the method of the invention for making an NPC is that amore uniformly distributed and homogenous mixture results within theextruder because the organic acid and the acid copolymer compositioncomprise a unit when added into the extruder as opposed to beingseparately fed into the extruder. Thus, one benefit is reduced incidenceof localized areas of heterogeneity in the resulting material.

Moreover, the risk of formulation error is lower when the ethylene acidcopolymer and organic acid are added as a unit into the extruder ratherthan being fed into it individually because as a unit, the weight ratioof the ingredients are fixed before addition to the extruder.

The present invention is also directed to a method of making a golf ballcomprising the steps of: providing a core or center; forming at leastone layer about the core or center (e.g. intermediate layer or outercore layer); and forming a cover about the layer; wherein at least oneof the core or center, a layer and the cover comprises an NPC formed byproviding an acid copolymer composition; soaking the acid copolymercomposition in an organic acid(s), or organic acid blend or derivativesthereof to form a soaked polymeric composition; providing a cationsource in an amount sufficient to neutralize a target level of acidgroups present; and melt processing the soaked polymeric composition andcation source.

The invention is further directed to a golf ball comprising: a core anda cover disposed about the core; wherein at least one of the core andthe cover comprises an NPC formed from a soaked polymeric compositioncomprising an acid copolymer soaked in an organic acid, whereinsubstantially all of the organic acid is absorbed within the acidcopolymer; and wherein a target level of acid groups present in thesoaked polymeric composition are neutralized with a cation source.

Embodiments are envisioned wherein a golf ball component may be formedin part from an NPC made according to the method of the invention asdetailed herein and also formed in part from a neutralized polymer madeby a conventional method of separately feeding organic acid and acidcopolymer into the extruder. Performing both methods may be particularlyadvantageous, for example, where a first chosen organic acid is soakablewithin the chosen acid copolymer while a second chosen organic acid isnot (it cannot be substantially absorbed with the chosen acidcopolymer).

Additionally, embodiments are envisioned wherein the golf ball componentcomprises a material formed by melt processing a mixture of soaked andnon-soaked polymeric ingredients. For example, in one non-limitingembodiment, a first portion of the polymeric ingredients (ethylene-acidcopolymer(s) or non-acid copolymer (the polymer)) is soaked, while asecond portion of the polymeric ingredient(s) is not soaked, and thesoaked and unsoaked portions are melt blended together in an extruder.Among other reasons, this method may allow for increasing thetemperature of the soak in the case of soaking a high melting polymericingredient.

In a different non-limiting embodiment, the invention is directed to agolf ball comprising: a core or center, at least one layer surroundingthe core or center and a cover disposed about the layer; wherein atleast one of a core or center, the layer and the cover comprises aneutralized polymeric composition (NPC) formed from a soaked polymericcomposition comprising an acid copolymer composition soaked in anorganic acid wherein substantially all of the organic acid is absorbedwithin the acid copolymer composition; and wherein the soaked polymericcomposition is melt processed with a cation source that is provided inan amount sufficient to neutralize at least a portion the acid copolymercomposition and organic acid.

Embodiments are also envisioned wherein sufficient cation source(s) isadded to neutralize up to about 100% or 120% or 150% or 175% or 200% ormore of acid groups present. In another embodiment additional organicacid is added sufficient to reduce the degree of neutralization to lessthan 70% or 70-80% or greater than 80% or 70-90% or 90-100% withoutadding more cation source.

In some embodiments, a soaking step at elevated temperature may furthercomprise incorporating an antioxidant package to prevent or inhibitoxidation of the organic acid or its derivatives and polymer. In thisregard, the antioxidant may for example be a liquid and/or dissolved inand thoroughly mixed with the organic acid prior to soaking the polymer.Suitable antioxidants include but are not limited to phenols, hinderedphenols, phosphites, propionates, triazines and thioethers. Suitableantioxidants include but are not limited to those disclosed hereinbelow. These and other antioxidants can be used alone or in combination.If used in combination, antioxidants can be added during the soakingstep and/or during melt blending.

For example, suitable antioxidants include: butylated hydroxy anisole(BHA); butylated hydroxy toluene (BHT); tris(nonylphenyl)phosphite(TNPP); diisooctylphosphite (DOPI); diisodecyl pentaerythritoldiphosphite; Irganox®1010-tetrakis[methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate)]methane;Irganox® 1076-octadecyl 3,5-di-tert-butyl-4-hydroxyhydrocinnamate;Irganox®1035-thiodiethylenebis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate); Irganox®245-ethylenebis(oxyethylene)bis-(3-tert-butyl-4-hydroxy-5-methylhydrocinnamate);Irganox® 1520-2-methyl-4,6-bis[(octylthio)methyl]phenol; Irganox®MD1024-1,2-bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamoyl)hydrazine;Irganox® PS802-distearyl thiodipropionate; Irganox®PS800-dilaurylthiodipropionate and Irganox®3125-3,5-di-tert-butyl-4-hydroxyhydrocinnamic acid triester with1,3,5-tris(2-hydroxyethyl)-S-triazine-2,4,6(1H,3H,5H)-trione. Irganox®is available from BASF.

Oxidation may also be reduced using other methods, for example, via anairtight container or other unit incorporating an inert gas blanket suchas Nitrogen or Argon.

In another embodiment, the acid copolymer composition is formed by meltprocessing together at least one acid copolymer and at least one polymerprior to soaking the composition in the organic acid. In a furtherembodiment, the acid copolymer and polymer are selected such that: (1)one ingredient has a substantially higher melting temperature than theother; and/or (2) one ingredient uptakes the organic acid much betterthan the other (i.e. one ingredient generally can hold higher levels ofthe organic acid than the other ingredient). Instance (1) enablessoaking of the acid copolymer composition at a higher temperature,thereby increasing the speed and amount of weight uptake of the organicacid and reducing the likelihood of blocking since the low melt polymerdoes not exist as a discrete pellet. Meanwhile, instance (2) providesfor easier material handling and reduces the likelihood of surgingwithin in the extruder, since the high weight uptake ingredient does nothave to carry more than its share of organic acid.

In this regard, an NPC suitable for use in a golf ball component may bemade by a method comprising the steps of: providing an acid copolymercomposition and an organic acid; wherein the acid copolymer compositionis formed by melt-processing at least one acid copolymer and at leastone polymer, the acid copolymer having a substantially higher meltingtemperature than the melting temperature of the polymer, or vice versa;and wherein the organic acid has a melting temperature that is less thanthe melting temperature of the acid copolymer composition; soaking themelt-processed acid copolymer composition in an organic acid at asoaking temperature that is less than the melting temperature of theacid copolymer composition to form a soaked polymeric composition;providing a cation source(s) in an amount sufficient to neutralize atleast a portion of the acid copolymer composition and organic acid; andmelt processing the soaked polymeric composition and cation source(s) toform the NPC.

In turn, a golf ball having at least one component comprising an NPC)may be made via a method comprising the steps of: providing a core orcenter; forming a layer about the center; and forming a cover about thelayer; wherein at least one of the core or center, the layer and thecover comprises an NPC formed by: providing an acid copolymercomposition formed by melt-processing at least one acid copolymer and atleast one polymer; soaking the acid copolymer composition in an organicacid having a melting temperature that is less than the meltingtemperature of the acid copolymer composition to form a soaked polymericcomposition; providing a cation source in an amount sufficient toneutralize at least a portion of the ethylene-acid copolymer compositionand organic acid; and melt processing the soaked polymeric compositionand cation source.

In one embodiment, the acid copolymer has a substantially higher meltingtemperature than the melting temperature of the polymer. In anotherembodiment, the polymer has a substantially higher melting temperaturethan the melting temperature of acid copolymer.

A resulting golf ball of the invention may comprise, for example, a coreor center and a cover disposed about the core or center; wherein atleast one of the core or center and the cover comprises a neutralizedpolymer composition (NPC) formed from a soaked polymeric compositioncomprising an acid copolymer composition soaked in an organic acid; theacid copolymer composition being formed by melt-processing at least oneacid copolymer and at least one polymer; and wherein a target level ofacid groups present in the soaked polymeric composition are neutralized.The NPC may be incorporated in any or all of a golf ball core or center,intermediate layer, cover and/or a coating, depending on golf ballstructure and desired properties.

In a different embodiment, a golf ball of the invention comprises a corehaving one or more layers and a cover disposed about the core; whereinat least one of the core and the cover comprises a neutralized polymercomposition (NPC) formed from a soaked polymeric composition comprisingan acid copolymer composition soaked in an organic acid; the acidcopolymer composition being formed by melt-processing at least one acidcopolymer and at least one polymer, wherein the acid copolymer and thepolymer have substantially different melting temperatures; whereinsubstantially all of the organic acid is absorbed within the acidcopolymer composition; and wherein a target level of acid groups presentin the soaked polymeric composition are neutralized.

In another embodiment, a golf ball of the invention comprises a corehaving one or more layers and a cover disposed about the core; whereinat least one of the core and the cover comprises a neutralized polymercomposition (NPC) formed from a soaked polymeric composition comprisingan acid copolymer composition soaked in an organic acid; whereinsubstantially all of the organic acid is absorbed within the acidcopolymer composition; and wherein a target level of acid groups presentin the soaked polymeric composition are neutralized such that the golfball has a CoR greater than 0.8 at 125% neutralization.

In yet another embodiment, the acid copolymer composition is formed from(a) a high acid ethylene/acrylic acid copolymer and (b) ethylene/acrylicacid/methyl acrylate copolymer; wherein the organic acid is comprised ofoleic acid; and wherein the cation source is comprised of magnesiumhydroxide in an amount sufficient to neutralize from about 95% to about125% of the acid copolymer composition and organic acid.

The term “high acid”, in connection with ethylene-acid copolymers shallrefer to an acid content of about 17% acid by weight or greater. In oneembodiment, the ethylene-acid copolymer is about 19% acid by weight orgreater, or about 20% acid by weight or greater, or about 20.5% acid byweight or greater, or about 22% acid by weight or greater, or about 24%acid by weight or greater, or about 27% acid by weight or greater.

Moreover, it is understood that an SPC, as described herein, may alsocomprise polymers which are not ultimately neutralized but are capableof substantially absorbing an organic acid and/or its derivatives. Forexample, in one non-limiting example, a golf ball of the invention maycomprise a core or center and a cover disposed about the core or center,wherein at least one of the core or center and the cover is formed froma soaked polymeric composition comprising an ethylene-acid copolymer anda polyolefin, soaked in a fatty acid ester wherein substantially all ofthe fatty acid ester is absorbed within the polyolefin. In anothernon-limiting example, fatty acid amides are absorbed within thepolyolefin.

In one embodiment, the invention is directed to a multi-piece golf ballconsisting of a center, a thermoplastic intermediate core layer, athermoplastic outer core layer, an inner cover layer and an outer coverlayer. The center is formed from a rubber composition and has a diameterof from 0.750 inches to 1.500 inches and has a geometric center hardnessof 30 Shore C or greater. The intermediate core layer is formed from aneutralized polymeric composition (NPC) formed from a soaked polymericcomposition and having a first flex modulus and a surface hardness of 30to 85 Shore C. The outermost core layer is formed from a second NPC andhas a flex modulus greater than the flex modulus of the intermediatecore layer and has a surface hardness of 35 to 90 Shore C. The innercover layer is comprised of a thermoplastic composition and has asurface hardness greater than 65 Shore D. Some examples of suitablematerials for the inner cover layer include ionomers, polyurethanes,polyamides, polyether block amides, polyester based thermoplasticelastomers and blends thereof. The surface hardness of the outer coverlayer is less the inner cover layer, and is formed from a compositionselected from the group consisting of polyurethanes, polyureas,ionomers, and copolymers and blends thereof.

In an additional embodiment, the present invention is directed to a golfball comprising a core and a cover. The core consists of a center and anouter core layer. The center comprises a neutralized polymericcomposition (NPC) formed from a soaked polymeric composition, and has adiameter of 0.625 to 1.375 inches and has a surface hardness of 30 to 85Shore C. The outer core layer is formed from a rubber composition, and athickness of 0.100 to 0.450 inches. The surface hardness of the outercore layer is in the range of 35 to 95 Shore C, and has a surfacehardness greater than the surface hardness of the center. The coverconsists of an outer cover layer and an inner cover layer, and thesurface hardness of the inner cover layer is greater than the surfacehardness of the outer cover layer. The inner cover layer is comprised ofa thermoplastic composition and has a surface hardness greater than 65Shore D. Some examples of suitable materials for the inner cover layerinclude ionomers, polyurethanes, polyamides, polyether block amides,polyester based thermoplastic elastomers and blends thereof. The outercover layer is formed from a composition selected from the groupconsisting of polyurethanes, polyureas, ionomers, and copolymers andblends thereof.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to neutralized polymer compositions(NPCs) and blends thereof for the use in golf equipment, preferably ingolf ball cores (centers and core layers), intermediate layers, and/orcovers. The acid moieties of the NPCs, typically acid copolymer organicacid blends, may be neutralized less than 70%, or 70-80%, or greaterthan 80%, 70-90% or 90-100%. The NPCs can be also be blended with asecond polymer ingredient, which, if containing an acid group, may beneutralized by the cation source. The second polymer ingredient, whichmay be partially or fully neutralized, may comprise ionomeric copolymersand terpolymers, ionomer precursors, thermoplastics, polyamides,polycarbonates, polyesters, polyurethanes, polyureas, thermoplasticelastomers, polybutadiene rubber, balata, metallocene-catalyzed polymers(grafted and non-grafted), single-site polymers, high-crystalline acidpolymers, cationic ionomers, and the like. NPCs may have a materialhardness of between about 10 Shore D and about 90 Shore D, and aflexural modulus of between about 3,000 psi and about 200,000 psi.

In one embodiment of the present invention the NPCs are ionomers and/ortheir acid precursors that are neutralized, either fully or partially,with the cation source. The acid copolymers may be α-olefin, such asethylene, C₃₋₈ α,β-ethylenically unsaturated carboxylic acid, such asacrylic and methacrylic acid, copolymers. They may optionally contain asoftening monomer, such as alkyl acrylate and alkyl methacrylate,wherein the alkyl groups have from 1 to 8 carbon atoms.

The acid copolymers can be described as E/X/Y copolymers where E isethylene, X is an α,β-ethylenically unsaturated carboxylic acid, and Yis a softening comonomer. In one embodiment, X is acrylic or methacrylicacid and Y is a C₁₋₈ alkyl acrylate or methacrylate ester. X may bepresent in an amount from about 1 to about 35 weight percent of thepolymer, or from about 5 to about 30 weight percent of the polymer, orfrom about 10 to about 20 weight percent of the polymer. Y may bepresent in an amount from about 0 to about 50 weight percent of thepolymer, or from about 5 to about 25 weight percent of the polymer, orfrom about 10 to about 20 weight percent of the polymer.

Specific acid-containing ethylene copolymers include, but are notlimited to, ethylene/acrylic acid/n-butyl acrylate, ethylene/methacrylicacid/n-butyl acrylate, ethylene/methacrylic acid/iso-butyl acrylate,ethylene/acrylic acid/iso-butyl acrylate, ethylene/methacrylicacid/n-butyl methacrylate, ethylene/acrylic acid/methyl methacrylate,ethylene/acrylic acid/methyl acrylate, ethylene/methacrylic acid/methylacrylate, ethylene/methacrylic acid/methyl methacrylate, andethylene/acrylic acid/n-butyl methacrylate, ethylene/acrylic acid/ethylacrylate, and ethylene/methacrylic acid/ethyl acrylate, ethylene/acrylicacid, and ethylene/methacrylic acid.

Ionomers are typically neutralized with a metal cation, such as Al, Li,Na, Mg, K, Ca, or Zn. It has been found that by adding sufficientorganic acid along with a cation source, the acid copolymer or ionomercan be neutralized, without losing processability, to a level muchgreater than with a cation source alone. The acid moieties may beneutralized less than 70%, 70-80%, or greater than 80% without losingprocessability. This is accomplished by melt-blending an ethyleneα,β-ethylenically unsaturated carboxylic acid copolymer, for example,with an organic acid or a salt of organic acid, and adding a sufficientamount of a cation source to increase the level of neutralization of allthe acid moieties.

The organic acids may be aliphatic, aromatic, di-acids, dimer acids,mono- or multi-functional, saturated, unsaturated, ormulti-unsaturatedorganic acids. Salts of these organic acids may also beemployed. The salts of organic acids may include barium, lithium,sodium, zinc, bismuth, chromium, cobalt, copper, potassium, strontium,titanium, tungsten, magnesium, cesium, iron, nickel, silver, aluminum,tin, or calcium. Salts of fatty acids such as stearic, behenic, erucic,oleic, linoleic or dimerized derivatives thereof are also suitable. Theorganic acids and salts of the present invention may be relativelynon-migratory (they do not bloom to the surface of the polymer underambient temperatures) and non-volatile (they do not volatilize attemperatures required for melt-blending).

In TABLE IA and TABLE IB below, seven soaked polymer compositions (SPCs)were formed and one SPC attempted as follows:

TABLE IA SPC Parameters SPC1 SPC2 SPC3 SPC4 SPC5 Escor ® AT-320* 2.4 2.42.4 2.4 2.4 (lbs.) Oleic acid** 1.6 — 1.6 1.6 1.6 (lbs.) Erucic acid***— 1.6 — — — (lbs.) Soak I Temp. 40 50 40 Rm. temp. Rm. temp. (° C.) SoakI Duration 96 36 48 24 >1 yr (hrs.) Soak II Temp. 50 60 50 60 — (° C.)Soak II Duration 24 24 96 24 — (hrs.) Soak III Temp. 55 65 — — — (° C.)Soak III Duration 24 24 — — — (hrs.) SPC Formed? Yes Yes Yes Yes, No,but minor pellets did adhesion not absorb observed substantially all ofthe fatty acid *Escor ® AT-320 is a ethylene/acrylic acid/methylacrylate terpolymer from ExxonMobil. **The melting point of oleic acidis about 13-18° C. ***The melting point of erucic acid is about 28-34°C.

TABLE IB SPC Parameters SPC6 SPC7 SPC8 5986* 1.7 — — (lbs.) AT320** 0.7— — (lbs.) AD1043*** — 3.2 — (lbs.) 5980i**** — — 1.8 (lbs.) 4700***** —— 0.6 (lbs.) Oleic acid 1.6 0.8 1.6 (lbs.) Soak I Temp. 40 50 40 (° C.)Soak I Duration 17.5 20 8 (hrs.) Soak II Temp. 50 — Rm. Temp. (° C.)Soak II Duration 11.5 — 16 (hrs.) Soak III Temp. 45 — 40 (° C.) Soak IIIDuration 4 — 10 (hrs.) Soak IV Temp. 40 — Rm. Temp. (° C.) Soak IVDuration 16 — 14 (hrs.) Soak V Temp. 50 — 50 (° C.) Soak V Duration 8.5— 8 (hrs.) SPC Formed? Yes Yes Yes *Primacor ® 5986 is a 20.5% acidethylene/acrylic acid copolymer manufactured by The Dow ChemicalCompany. **Escor ® AT-320 is an ethylene/acrylic acid/methyl acrylateterpolymer from ExxonMobil. ***HPC ® AD1043 is an ionomer manufacturedby DuPont. ****Primacor ® 5980i is a 20.5% acid ethylene/acrylic acidcopolymer manufactured by The Dow Chemical Company. *****Lotader ® 4700is an ethylene/ethyl acrylate copolymer manufactured by Arkema.

In each of the examples of TABLE IA and TABLE IB, an ethylene/acidcopolymer was soaked in an organic acid. For example, soaked polymericcompositions SPC1, SPC3, SPC4 and SPC5 of TABLE IA were formed bysoaking AT320 pellets in oleic acid in a weight ratio of 3:2,respectively. Each of the processes shown in TABLE 1A and TABLE 1Bdiffer in at least one of the following respects: by the polymer; and/orthe number of soaking steps performed; and/or the soaking temperaturefor each step; and/or the duration of each step; and/or the totalprocess soaking time. For example, in examples SPC1, SPC2, SPC3, SPC4,and SPC5, the acid copolymer is Escor®AT-320, whereas, SPC6 incorporatesa polymer blend of Escor®AT-320 and Primacor® 5986. While SPC1 and SPC3share the same total process soaking duration of 144 hours, example SPC1has three different soaking steps that are performed at three differentsoaking temperatures, whereas in example SPC3, only two differentsoaking steps were performed at two different soaking temperatures. Inexample SPC 8, the two polymers were first melt-blended prior to thesoaking step.

Notably, in examples SPC4, SPC5 and SPC8, at least one soaking step wasperformed at room temperature (about 20-23° C.), which is very close toor is at the melting point for the chosen organic acid (18-32° C.).

The process of example SPC5, performed in a single soaking step at roomtemperature, failed to produce an SPC due to insufficient fatty acidabsorption. In contrast, in example SPC4, some adhesion was observed,but not sufficient enough to constitute blocking. In example SCP4, a twostep soaking process was performed, with one step being performed atroom temperature and a second soaking step performed at a soakingtemperature well above the melting temperature of oleic acid.

The SPCs of examples SPC1, SPC2, SPC3, SPC6 and SPC 7 as formulated inTABLE IA and TABLE IB were neutralized and injection molded into 1.55″spheres. The compression and CoR were then evaluated with respect toeach sphere. These results are recorded in TABLE II below.

TABLE II Polymer Composition/ % Neutralization, Compression, CoR@125Polymer (target) Atti ft/sec SPC1 125 67 0.798 SPC2 105 60 0.803 SPC3 9262 0.782 SPC4* — — — SPC5** — — — SPC6 105 111 0.857 SPC7 63 −17 0.503SPC8*** — — — *There is no data for SPC4 because solid spheres were notmade. **There is no data for SPC5 because the material could not beextruded. ***In progress.

Herein, while each SPCs of examples SPC1, SPC2, and SPC3, SPC6 and SPC7of TABLE IA and TABLE IB were neutralized via twin screw extrusion, anymethod known in the art may also be used to neutralize an SPC of theinvention.

Several different methods can be used to measure compression, includingAtti compression, Riehle compression, load/deflection measurements at avariety of fixed loads and offsets, and effective modulus. See, e.g.,Compression by Any Other Name, Science and Golf IV, Proceedings of theWorld Scientific Congress of Golf (Eric Thain ed., Routledge, 2002) (“J.Dalton”). The term compression, as used herein, refers to Atticompression and is measured using an Atti compression test device. Atticompression units can be converted to Riehle (cores), Riehle (balls),100 kg deflection, 130-10 kg deflection or effective modulus using theformulas set forth in J. Dalton.

According to one aspect of the present invention, the golf ball isformulated to have a compression of between about 40 and about 120.

The distance that a golf ball would travel upon impact is a function ofthe coefficient of restitution (CoR) and the aerodynamic characteristicsof the ball. For golf balls, CoR has been approximated as a ratio of thevelocity of the golf ball after impact to the velocity of the golf ballprior to impact. The CoR varies from 0 to 1.0. A CoR value of 1.0 isequivalent to a perfectly elastic collision, that is, all the energy istransferred in the collision. A CoR value of 0.0 is equivalent to aperfectly inelastic collision—that is, all of the energy is lost in thecollision.

CoR, as used herein, is determined by firing a golf ball or golf ballsubassembly (e.g., a golf ball core) from an air cannon at two givenvelocities and calculating the CoR at a velocity of 125 ft/s. Ballvelocity is calculated as a ball approaches ballistic light screenswhich are located between the air cannon and a steel plate at a fixeddistance. As the ball travels toward the steel plate, each light screenis activated, and the time at each light screen is measured. Thisprovides an incoming transit time period inversely proportional to theball's incoming velocity. The ball impacts the steel plate and reboundsthrough the light screens, which again measure the time period requiredto transit between the light screens. This provides an outgoing transittime period inversely proportional to the ball's outgoing velocity. CoRis then calculated as the ratio of the outgoing transit time period tothe incoming transit time period, CoR=V_(out)/V_(in)=T_(in)/T_(out).Preferably, a golf ball according to the present invention has a CoR ofat least about 0.770, more preferably, at least about 0.790.

The NPCs produced by the methods of the present invention may berelatively soft or relatively hard, depending on the desired propertiesof the resulting golf ball incorporating the material. For example,relatively soft NPCs produced by the method of the invention may have amaterial hardness of about 10 Shore D to about 80 Shore D, or about 80Shore D or less, or have a Shore D hardness of 55 or less or a Shore Dhardness within the range having a lower limit of 10 or 20 or 30 or 37or 39 or 40 or 45 and an upper limit of 48 or 50 or 52 or 55 or 60 or80. Meanwhile, relatively hard NPCs of the present invention have aShore D hardness of 35 or greater, or have a Shore D hardness of 45 orgreater or a Shore D hardness with the range having a lower limit of 45or 50 or 55 or 57 or 58 or 60 or 65 or 70 or 75 and an upper limit of 80or 85 or 90 or 95 Shore D.

For purposes of the present disclosure, material hardness is measuredaccording to ASTM D2240 and involves measuring the hardness of a flat“slab” or “button” formed of the material. It should be understood thatthere is a fundamental difference between “material hardness” and“hardness as measured directly on a golf ball.” Hardness as measureddirectly on a golf ball (or other spherical surface) typically resultsin a different hardness value from material hardness. This difference inhardness values is due to several factors including, but not limited to,ball construction (i.e., core type, number of core and/or cover layers,etc.), ball (or sphere) diameter, and the material composition ofadjacent layers. It should also be understood that the two measurementtechniques are not linearly related and, therefore, one hardness valuecannot easily be correlated to the other. Unless stated otherwise, thehardness values given herein are material hardness values measuredaccording to ASTM D2240, with all values reported following 14 days ofaging at 50% relative humidity and 23° C.A calibrated, digitaldurometer, capable of reading to 0.1 hardness units is used for allhardness measurements and is set to record hardness reading at themaximum reading. The digital durometer must be attached to, and its footmade parallel to, the base of an automatic stand, such that the weighton the durometer and attack rate conform to ASTM D-2240.

A core in a golf ball of the invention may be a solid single core.Alternatively, the core may be a multi-layered core comprising a centerand at least one outer core layer. The center of the core may be solid,liquid-filled or hollow sphere. A core may be surrounded by one or moreintermediate and/or cover layers. A core may even include a solid orliquid center around which tensioned elastomeric material is wound.

In a golf ball of the invention, the core may comprise a compositionincluding at least one thermoset base rubber, such as a polybutadienerubber, cured with at least one peroxide and at least one reactiveco-agent, which can be a metal salt of an unsaturated carboxylic acid,such as acrylic acid or methacrylic acid, a non-metallic coagent, ormixtures thereof. A suitable antioxidant may be included in thecomposition. An optional soft and fast agent (and sometimes acis-to-trans catalyst), such as an organosulfur or metal-containingorganosulfur compound, can also be included in the core formulation.

Other ingredients that are known to those skilled in the art may beused, and are understood to include, but not be limited to,density-adjusting fillers, process aides, plasticizers, blowing orfoaming agents, sulfur accelerators, and/or non-peroxide radicalsources.

The base thermoset rubber, which can be blended with other rubbers andpolymers, may include a natural or synthetic rubber. One base rubber is1,4-polybutadiene having a cis structure of at least 40%, or greaterthan 80%, or greater than 90%. Examples of desirable polybutadienerubbers include BUNA®: CB 21, CB 22, CB 23, CB 24, CB 25, CB 29 MES, CBNd 40, CB Nd 40 H, CB Nd 60, CB 55 NF, CB 60, CB 45 B, CB 55 B, CB 55 H,CB 55 L, CB 70 B, CB 1220, CB 1221, CB 1203, and CB 45, commerciallyavailable from LANXESS Corporation; UBEPOL® 360L and UBEPOL® 150L andUBEPOL-BR rubbers, commercially available from UBE Industries, Ltd. ofTokyo, Japan; KINEX® 7245, KINEX® 7265, and BUDENE® 1207 and 1208,commercially available from Goodyear of Akron, Ohio; SE BR-1220;Europrene® NEOCIS® BR 40 and BR 60, commercially available from PolimeriEuropa; and BR 01, BR 730, BR 735, BR 11, and BR 51, commerciallyavailable from Japan Synthetic Rubber Co., Ltd; PETROFLEX® BRNd-40;Ubepol® sold by Ube Industries Inc, Japan, BST sold by BST Elastomers,Thailand; IPCL sold by Indian Petrochemicals Ltd, India; and KARBOCHEM®ND40, ND45, Nitsu and ND60, commercially available from Karbochem orKarbochem Ltd of South Africa; Petroflex of Brazil; LG of Korea; andKuhmo Petrochemical of Korea.

The base rubber may also comprise high or medium Mooney viscosityrubber, or blends thereof. A “Mooney” unit is a unit used to measure theplasticity of raw or unvulcanized rubber. The plasticity in a “Mooney”unit is equal to the torque, measured on an arbitrary scale, on a diskin a vessel that contains rubber at a temperature of 100° C. and rotatesat two revolutions per minute. The measurement of Mooney viscosity isdefined according to ASTM D-1646.

The Mooney viscosity range is preferably greater than about 30, or inthe range from about 40 to about 80, or in the range from about 40 toabout 60. Polybutadiene rubber with higher Mooney viscosity may also beused, so long as the viscosity of the polybutadiene does not reach alevel where the high viscosity polybutadiene clogs or otherwiseadversely interferes with the manufacturing machinery. It iscontemplated that polybutadiene with viscosity less than 65 Mooney canbe used with the present invention.

If desired, the polybutadiene can also be mixed with other elastomersknown in the art such as natural rubber, polyisoprene rubber and/orstyrene-butadiene rubber in order to modify the properties of the core.Other suitable base rubbers include thermosetting materials such as,ethylene propylene diene monomer rubber, ethylene propylene rubber,butyl rubber, halobutyl rubber, hydrogenated nitrile butadiene rubber,nitrile rubber, and silicone rubber. When a mixture of elastomers isused, the amounts of other constituents in the core composition aretypically based on 100 parts by weight of the total elastomer mixture.

Thermoplastic elastomers (TPE) may also be used to modify the propertiesof the core layers, or the uncured core layer stock by blending with thebase thermoset rubber. These TPEs include natural or synthetic balata,or high trans-polyisoprene, high trans-polybutadiene, or any styrenicblock copolymer, such as styrene ethylene butadiene styrene,styrene-isoprene-styrene, etc., a metallocene or other single-sitecatalyzed polyolefin such as ethylene-octene, or ethylene-butene, orthermoplastic polyurethanes (TPU), including copolymers, with e.g.silicone.

Suitable peroxide initiating agents include dicumyl peroxide;2,5-dimethyl-2,5-di(t-butylperoxy)hexane;2,5-dimethyl-2,5-di(t-butylperoxy)hexyne;2,5-dimethyl-2,5-di(benzoylperoxy)hexane;2,2′-bis(t-butylperoxy)-di-iso-propylbenzene;1,1-bis(t-butylperoxy)-3,3,5-trimethyl cyclohexane; n-butyl4,4-bis(t-butyl-peroxy)valerate; t-butyl perbenzoate; benzoyl peroxide;n-butyl 4,4′-bis(butylperoxy) valerate; di-t-butyl peroxide; or2,5-di-(t-butylperoxy)-2,5-dimethyl hexane, lauryl peroxide, t-butylhydroperoxide, c′-c′ bis(t-butylperoxy) diisopropylbenzene,di(2-t-butyl-peroxyisopropyl)benzene, di-t-amyl peroxide, di-t-butylperoxide. Commercially-available peroxide initiating agents includeDICUP™ family of dicumyl peroxides (including DICUP™ R, DICUP™ 40C andDICUP™ 40KE) available from Crompton (Geo Specialty Chemicals). Similarinitiating agents are available from AkroChem, Lanxess, Flexsys/Harwickand R. T. Vanderbilt. Another commercially-available and preferredinitiating agent is TRIGONOX™ 265-50B from Akzo Nobel, which is amixture of 1,1-di(t-butylperoxy)-3,3,5-trimethylcyclohexane anddi(2-t-butylperoxyisopropyl) benzene. TRIGONOX™ peroxides are generallysold on a carrier compound.

Suitable reactive co-agents include, but are not limited to, metal saltsof diacrylates, dimethacrylates, and monomethacrylates suitable for usein this invention include those wherein the metal is zinc, magnesium,calcium, barium, tin, aluminum, lithium, sodium, potassium, iron,zirconium, and bismuth. Zinc diacrylate (ZDA) is preferred, but thepresent invention is not limited thereto. ZDA provides golf balls with ahigh initial velocity. The ZDA can be of various grades of purity. Forthe purposes of this invention, the lower the quantity of zinc stearatepresent in the ZDA the higher the ZDA purity. Suitable commerciallyavailable zinc diacrylates include those from Cray Valley.

Additional preferred co-agents that may be used alone or in combinationwith those mentioned above include, but are not limited to,trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, andthe like. It is understood by those skilled in the art, that in the casewhere these co-agents may be liquids at room temperature, it may beadvantageous to disperse these compounds on a suitable carrier topromote ease of incorporation in the rubber mixture.

Antioxidants are compounds that inhibit or prevent the oxidativebreakdown of elastomers, and/or inhibit or prevent reactions that arepromoted by oxygen radicals. Some exemplary antioxidants that may beused in the present invention include, but are not limited to, quinolinetype antioxidants, amine type antioxidants, and phenolic typeantioxidants. A preferred antioxidant is2,2′-methylene-bis-(4-methyl-6-t-butylphenol) available as VANOX® MBPCfrom R.T. Vanderbilt. Other polyphenolic antioxidants include VANOX® L(a reaction product of p-cresol and dicyclopentadiene), VANOX® SKT(3,5-di-tert-butyl-4-hydroxyhydrocinnamic acid triester of1,3,5-(2-hydroxyethyl)-s-triazine-2,4,6(1H,3H,5H)trione), VANOX® SWP(4,4′-butylidenebis(6-tert-butyl-3-methylphenol)), VANOX® 13(Polyalkylpolyphenolphosphite) and VANOX® 1290(2,2′-ethylidenebis-(4,6-di-tert-butylphenol)).

Thermoset rubber compositions incorporated in golf balls of the presentinvention may also include an optional soft and fast agent. As usedherein, “soft and fast agent” means any compound or a blend thereof thatthat is capable of making a core 1) be softer (lower compression) atconstant CoR or 2) have a higher CoR at equal compression, or anycombination thereof, when compared to a core equivalently preparedwithout a soft and fast agent. Suitable soft and fast agents include,but are not limited to, organosulfur or metal-containing organosulfurcompounds, an organic sulfur compound, including mono, di, andpolysulfides, a thiol, or mercapto compound, an inorganic sulfidecompound, a Group VIA compound, or mixtures thereof. The soft and fastagent ingredient may also be a blend of an organosulfur compound and aninorganic sulfide compound. Examples include pentachlorobenzenethiol(PCTP) and salts thereof, including but not limited to Zn and ammonium.

As used herein when referring to the invention, the term “organosulfurcompound(s)” refers to any compound containing carbon, hydrogen, andsulfur, where the sulfur is directly bonded to at least one carbon. Asused herein, the term “sulfur compound” means a compound that iselemental sulfur, polymeric sulfur, or a combination thereof. It shouldbe further understood that the term “elemental sulfur” refers to thering structure of S₈ and that “polymeric sulfur” is a structureincluding at least one additional sulfur relative to elemental sulfur.

Fillers may also be added to the thermoset rubber composition of thecore to adjust the density of the composition, up or down. Typically,fillers include materials such as tungsten, zinc oxide, barium sulfate,silica, calcium carbonate, zinc carbonate, metals, metal oxides andsalts, regrind (e,g, recycled core material typically ground to about 30mesh particle).

Fillers added to one or more portions of the golf ball typically includeprocessing aids or compounds to affect rheological and mixingproperties, density-modifying fillers, tear strength, or reinforcementfillers, and the like. The fillers are generally inorganic, and suitablefillers include numerous metals or metal oxides, such as zinc oxide andtin oxide, as well as barium sulfate, zinc sulfate, calcium carbonate,barium carbonate, clay, tungsten, tungsten carbide, an array of silicas,and mixtures thereof. Fillers may also include various foaming agents orblowing agents which may be readily selected by one of ordinary skill inthe art. Fillers may include polymeric, ceramic, metal, and glassmicrospheres may be solid or hollow, and filled or unfilled. Fillers aretypically also added to one or more portions of the golf ball to modifythe density thereof to conform to uniform golf ball standards. Fillersmay also be used to modify the weight of the center or at least oneadditional layer for specialty balls, e.g., a lower weight ball ispreferred for a player having a low swing speed.

The polybutadiene and/or any other base rubber or elastomer system mayalso be foamed, or filled with hollow microspheres or with expandablemicrospheres which expand at a set temperature during the curing processto any low specific gravity level. Other ingredients such as sulfuraccelerators, e.g., tetramethylthiuram di, tri, or tetrasulfide, and/ormetal-containing organosulfur ingredients may also be used according tothe invention. Suitable metal-containing organosulfur acceleratorsinclude, but are not limited to, cadmium, copper, lead, and telluriumanalogs of diethyldithiocarbamate, diamyldithiocarbamate, anddimethyldithiocarbamate, or mixtures thereof. Other ingredients such asprocessing aids e.g., fatty acids and/or their metal salts, processingoils, dyes and pigments, as well as other additives known to one skilledin the art may also be used in the present invention in amountssufficient to achieve the purpose for which they are typically used.

The core in a golf ball of the invention may be a single core having adiameter of about 1.0 inch to about 1.64 inches, preferably about 1.30inches to about 1.620, and more preferably about 1.40 inches to about1.60 inches.

Cores for the golf balls of the present invention may alternatively havean outer core layer formed about a center, referred to as a “dual core”arrangement. In a multi-layer embodiment, the center has an outerdiameter of about 0.25 inches to about 1.40 inches, or about 0.8 inchesto about 1.30 inches, or about 1.00 inches to about 1.20 inches. Thecore may have an outer diameter of about 1.40 inches to about 1.64inches, or about 1.50 inches to about 1.60 inches, or about 1.53 inchesto about 1.58 inches.

An intermediate layer may be disposed about the core, with the coverlayer formed around the intermediate layer. A golf ball of the inventionhave any overall diameter, but a generally preferred diameter is 1.68inches-which meets the USGA (United States Golf Association) standard.

The cover may be formed of a single layer or multiple cover layers suchas an inner cover layer and an outer cover layer. The cover may beformed from a castable polyurea or a castable polyurethane, i.e.,meaning covers comprising castable polyurea (100% urea linkages/nourethane linkages); castable polyurethane (100% urethane linkages/nourea linkages); castable hybrid poly(urethane/urea) (the prepolymer isall urethane linkages and is cured with an amine); and castable hybridpoly(urea/urethane) (the prepolymer is all urea linkages and is curedwith a polyol).

While the inventive golf ball may be formed from a variety of differingand conventional cover materials (both intermediate layer(s) and outercover layer), preferred cover materials include, but are not limited to:

(1) Polyurethanes, such as those prepared from polyols or polyamines anddiisocyanates or polyisocyanates and/or their prepolymers, and thosedisclosed in U.S. Pat. Nos. 5,334,673 and 6,506,851;(2) Polyureas, such as those disclosed in U.S. Pat. Nos. 5,484,870 and6,835,794; and(3) Polyurethane-urea hybrids, blends or copolymers comprising urethaneor urea segments.

Suitable polyurethane or polyurea compositions comprise a reactionproduct of at least one polyisocyanate and at least one curing agent.The curing agent can include, for example, one or more polyamines, oneor more polyols, or a combination thereof. The polyisocyanate can becombined with one or more polyols or polyamines to form a prepolymer,which is then combined with the at least one curing agent. Suitablepolyurethanes are described in U.S. Patent Application Publication No.2005/0176523, which is incorporated by reference in its entirety.

Alternatively, other suitable polymers include partially or fullyneutralized ionomer, metallocene, or other single-site catalyzedpolymer, polyester, polyamide, non-ionomeric thermoplastic elastomer,copolyether-esters, copolyether-amides, polycarbonate, polybutadiene,polyisoprene, polystryrene block copolymers (such asstyrene-butadiene-styrene), styrene-ethylene-propylene-styrene,styrene-ethylene-butylene-styrene, and the like, and blends thereof.Thermosetting polyurethanes or polyureas are suitable for the outercover layers of the golf balls of the present invention.

Another cover material comprises a castable or reaction injectionmoldable polyurethane, polyurea, or copolymer or hybrid ofpolyurethane/polyurea. This cover is thermosetting but may be athermoplastic, having a Shore D hardness of about 20 to about 70, morepreferably about 30 to about 65 and most preferably about 35 to about60. A moisture vapor barrier layer, such as disclosed in U.S. Pat. Nos.6,632,147; 6,932,720; 7,004,854; and 7,182,702, all of which areincorporated by reference herein in their entirety, are optionallyemployed between the cover layer and the core.

Any of the embodiments herein may have any known dimple number andpattern such as 252 to 456 or 330 to 392, for example. The dimples maycomprise any width, depth, and edge angle disclosed in the prior art andthe patterns may comprises multitudes of dimples having differentwidths, depths and edge angles. The parting line configuration of saidpattern may be either a straight line or a staggered wave parting line(SWPL).

Other than in the operating examples, or unless otherwise expresslyspecified, all of the numerical ranges, amounts, values and percentagessuch as those for amounts of materials and others in the specificationmay be read as if prefaced by the word “about” even though the term“about” may not expressly appear with the value, amount or range.Accordingly, unless indicated to the contrary, the numerical parametersset forth in the specification and attached claims are approximationsthat may vary depending upon the desired properties sought to beobtained by the present invention. At the very least, and not as anattempt to limit the application of the doctrine of equivalents to thescope of the claims, each numerical parameter should at least beconstrued in light of the number of reported significant digits and byapplying ordinary rounding techniques.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contain certainerrors necessarily resulting from the standard deviation found in theirrespective testing measurements. Furthermore, when numerical ranges ofvarying scope are set forth herein, it is contemplated that anycombination of these values inclusive of the recited values may be used.

While it is apparent that the illustrative embodiments of the inventiondisclosed herein fulfill the objective stated above, it is appreciatedthat numerous modifications and other embodiments may be devised bythose skilled in the art. Therefore, it will be understood that theappended claims are intended to cover all such modifications andembodiments, which would come within the spirit and scope of the presentinvention.

What is claimed is:
 1. A method of making a neutralized polymercomposition (NPC) suitable for use in a golf ball component comprisingthe steps of: providing an acid copolymer composition; soaking the acidcopolymer composition in an organic acid to form a soaked polymericcomposition; providing a cation source in an amount sufficient toneutralize at least a portion of the acid copolymer composition andorganic acid; and melt processing the soaked polymeric composition andcation source to form the NPC.
 2. The method of claim 1, wherein theacid copolymer composition comprises at least one acid-containingethylene copolymer.
 3. The method of claim 2, wherein theacid-containing ethylene copolymer is selected from the group consistingof: ethylene/acrylic acid/n-butyl acrylate, ethylene/methacrylicacid/n-butyl acrylate, ethylene/methacrylic acid/iso-butyl acrylate,ethylene/acrylic acid/iso-butyl acrylate, ethylene/methacrylicacid/n-butyl methacrylate, ethylene/acrylic acid/methyl methacrylate,ethylene/acrylic acid/methyl acrylate, ethylene/methacrylic acid/methylacrylate, ethylene/methacrylic acid/methyl methacrylate, andethylene/acrylic acid/n-butyl methacrylate, ethylene/acrylic acid/ethylacrylate, ethylene/methacrylic acid/ethyl acrylate, ethylene/acrylicacid, and ethylene/methacrylic acid.
 4. The method of claim 1, whereinthe organic acid is selected from the group consisting of aliphaticorganic acids, aromatic organic acids, saturated mono- ormulti-functional organic acids, unsaturated mono- or multi-functionalorganic acids, and multi-unsaturated mono- or multi-functional organicacids.
 5. The method of claim 1, wherein the organic acid comprisesstearic acid, behenic acid, erucic acid, oleic acid, linoleic acid,linolenic acid or dimerized derivatives thereof.
 6. The method of claim1, wherein the soaking step is performed at a soaking temperature offrom about 20° C. to about 100° C.
 7. The method of claim 1, wherein thesoaked polymer composition comprises the organic acid and acid copolymercomposition in a weight ratio of about 2:3.
 8. The method of claim 1,wherein the soaked polymer composition comprises the organic acid andacid copolymer composition in a weight ratio of from about 1:9 to about1:1.
 9. The method of claim 1, wherein the acid copolymer composition isformed from (a) a high acid ethylene/acrylic copolymer and (b)ethylene/acrylic acid/methyl acrylate copolymer, blended; wherein theorganic acid is comprised of oleic acid; and wherein the cation sourceis comprised of magnesium hydroxide in an amount sufficient toneutralize from about 95% to about 125% of the acid copolymercomposition and organic acid.
 10. A method of making a golf ball havingat least one component comprising a neutralized polymer composition(NPC), comprising the steps of: providing a center; forming a layerabout the center; and forming a cover about the layer; wherein at leastone of the center, the layer and the cover comprises an NPC formed by:providing an acid copolymer composition; soaking the acid copolymercomposition in an organic acid to form a soaked polymeric composition;providing a cation source in an amount sufficient to neutralize the acidcopolymer composition and organic acid; and melt processing the soakedpolymeric composition and cation source.
 11. The method of claim 10,wherein the acid copolymer composition comprises an acid-containingethylene copolymer selected from the group consisting of:ethylene/acrylic acid/n-butyl acrylate, ethylene/methacrylicacid/n-butyl acrylate, ethylene/methacrylic acid/iso-butyl acrylate,ethylene/acrylic acid/iso-butyl acrylate, ethylene/methacrylicacid/n-butyl methacrylate, ethylene/acrylic acid/methyl methacrylate,ethylene/acrylic acid/methyl acrylate, ethylene/methacrylic acid/methylacrylate, ethylene/methacrylic acid/methyl methacrylate, andethylene/acrylic acid/n-butyl methacrylate, ethylene/acrylic acid/ethylacrylate, and ethylene/methacrylic acid/ethyl acrylate, ethylene/acrylicacid, and ethylene/methacrylic acid.
 12. The method of claim 10, whereinthe organic acid is selected from the group consisting of aliphaticorganic acids, aromatic organic acids, saturated mono- ormulti-functional organic acids, unsaturated mono- or multi-functionalorganic acids, multi-unsaturated mono- or multi-functional organicacids, stearic acid, behenic acid, erucic acid, oleic acid, linoleicacid, linolenic acid or dimerized derivatives thereof.
 13. The method ofclaim 10, wherein the soaking step is performed at a soaking temperatureof from about 20° C. to about 100° C.
 14. The method of claim 10,wherein the soaked polymeric composition comprises the organic acid andacid copolymer composition in a weight ratio of about 2:3.
 15. Themethod of claim 10, wherein the soaked polymeric composition comprisesthe organic acid and acid copolymer composition in a weight ratio offrom about 1:9 to about 1:1.
 16. A golf ball comprising: a core havingone or more layers and a cover disposed about the core; wherein at leastone of the core and the cover comprises a neutralized polymercomposition (NPC) formed from a soaked polymeric composition comprisingan acid copolymer composition soaked in an organic acid; whereinsubstantially all of the organic acid is absorbed within the acidcopolymer composition; and wherein at least a portion of acid groupspresent in the soaked polymeric composition are neutralized.
 17. Thegolf ball of claim 16, wherein the acid copolymer composition comprisesan acid containing ethylene copolymer selected from the group consistingof: ethylene/acrylic acid/n-butyl acrylate, ethylene/methacrylicacid/n-butyl acrylate, ethylene/methacrylic acid/iso-butyl acrylate,ethylene/acrylic acid/iso-butyl acrylate, ethylene/methacrylicacid/n-butyl methacrylate, ethylene/acrylic acid/methyl methacrylate,ethylene/acrylic acid/methyl acrylate, ethylene/methacrylic acid/methylacrylate, ethylene/methacrylic acid/methyl methacrylate, andethylene/acrylic acid/n-butyl methacrylate, ethylene/acrylic acid/ethylacrylate, and ethylene/methacrylic acid/ethyl acrylate, ethylene/acrylicacid, and ethylene/methacrylic acid.
 18. The golf ball of claim 16,wherein the organic acid is selected from the group consisting ofaliphatic organic acids, aromatic organic acids, saturated mono- ormulti-functional organic acids, unsaturated mono- or multi-functionalorganic acids, and multi-unsaturated mono- or multi-functional organicacids, stearic acid, behenic acid, erucic acid, oleic acid, linoleicacid, linolenic aicd or dimerized derivatives thereof.
 19. The golf ballof claim 16, wherein the soaked polymer composition comprises theorganic acid and acid copolymer composition in a weight ratio of fromabout 1:9 to about 1:1.
 20. The golf ball of claim 16, wherein thesoaked polymeric composition comprises the organic acid and acidcopolymer composition in a weight ratio of about 2:3.
 21. The golf ballof claim 16, wherein the acid copolymer composition is formed from (a) ahigh acid ethylene acrylic copolymer and (b) ethylene acrylic acid andmethyl acrylate, blended; wherein the organic acid is comprised of oleicacid; and wherein the cation source is comprised of magnesium hydroxidein an amount sufficient to neutralize from about 95% to about 125% ofthe acid copolymer composition and organic acid.